Corrugated cardboard composite is used in a large number of applications. It is particularly desirable in packaging applications because it is rugged and has high dimensional and structural integrity. Corrugated boxes are used to package a variety of goods and are commonly stacked upon one another. The boxes must have sufficient stacking strength to maintain their shape while supporting the stacked corrugated boxes with goods stored therein. Therefore, corrugated boxes are commonly constructed so as to utilize the strength of corrugated board. Corrugated board typically includes a corrugated medium affixed to at least one liner, or alternatively, sandwiched between a top liner and a bottom liner. Corrugated boxes constructed from corrugated board, with the flutes oriented vertically, generally have sufficient stacking strength.
Typically, corrugated cardboard is formed by producing a corrugated sheet that is initially bonded along one side to a single face. Adhesive is then applied to the crests of the flutes remote from the single face by an applicator roll of a glue machine. Thereafter, a second face is applied to the adhesive on the flutes to produce a composite structure in which corrugations extend between and are bonded to spaced-apart faces.
In some instances, multiple-layer cardboard is produced in which more than one corrugated sheet is adhesively attached to additional faces so that, for example, a central flat face is bonded to a corrugated sheet on each side thereof, and outer flat faces are bonded to the sides of the two corrugated sheets remote from the central face. In another example, the flutes of one corrugated sheet can be adhesively attached to the flutes of another corrugated sheet.
Typically, a single face liner is a planar piece of paperboard while the corrugated medium is a fluted piece of paperboard. Conventionally, the corrugated medium is formed from a generally planar paperboard web that is maintained under a tensile force and is continuously fed into a corrugating machine that forms the flutes. The planar paperboard web is generally fed into the corrugating machine with the paperboard fibers oriented in a longitudinal direction generally parallel to the web direction. However, conventional corrugating machines generally form the flutes in a transverse direction relative to the longitudinal direction of the paperboard web. In other words, the flutes are formed in a “non-machine-direction” that is transverse to the fibers of the paperboard. The “machine direction” is defined by the direction in which fibers pass through the paper machine. Thus, flutes formed in a “non-machine direction” must re-orient the paper fibers, which can lead to reduced strength.
Accordingly, it would be beneficial to provide a corrugating machine that can form the flutes in the paperboard in the “machine direction” and generally parallel to the direction of the paper fibers (e.g., linear or longitudinal fluting). Flutes formed longitudinally in the “machine direction” can provide a significant strength increase in the resulting corrugated board. Moreover, it would be beneficial to provide a corrugating machine that can permit relatively quick adjustment of the flute sizes to provide various types of corrugated board.